Hydroformylation, which was discovered by Otto Roelen in Germany in 1938, generates linear (normal) and branched (iso) aldehydes, a carbon number of which is increased by one, by reacting various olefins with carbon monoxide (CO) and hydrogen (H2), which are often referred to as synthesis gases, in the presence of a homogeneous organometallic catalyst and ligand.
Hydroformylation reaction, commonly known as oxo reaction, is an industrially important homogeneous catalytic reaction. Through such oxo reaction, various aldehydes including alcohol derivatives are produced throughout the world.
Various aldehydes synthesized by oxo reaction may be oxidized or hydrogenated after aldol condensation and the like to be transformed into various acids and alcohols containing long alkyl groups. Particularly, hydrogenated alcohols of aldehydes produced by such oxo reaction are called oxo alcohols. Such oxo alcohol is industrially, widely used as a solvent, an additive, a raw material of various plasticizers, a synthetic lubricating oil, and the like.
In this regard, since the ratio of linear aldehyde (normal-aldehyde) derivatives among aldehydes produced by the oxo reaction is high, most research into catalysts has focused on increasing the proportion of the linear aldehyde derivatives. However, in recent years, demand for iso-aldehydes has increased due to development of, for example, isobutyric acid, neopentyl glycol (NPG), 2,2,4-trimethyl-1,3-pentanediol, isovaleric acid, and the like, which use a branched aldehyde derivative (iso-aldehyde) as a raw material, and thus, research to increase selectivity for branched aldehyde derivatives is underway. Accordingly, there is a need for development of a catalyst having superior stability and activity while lowering an n/i ratio in aldehyde.